I honestly can't tell if it's really floating freely in there (she says she only scrapes the front, flat of the tanks.), or if it's simply on the walls and clinging to the bamboo. Even so, don't you supposed that in the wild there were mossy, muddy conditions in water? I don't think it would really hamper their swimming, and I also think that it probably wouldn't clog their gills. I could be wrong, but if it could, I'd think that bettas in general wouldn't have made it very far up the evolutionary chain. *shrug*